The present invention relates to an electromagnetic valve.
An electromagnetic valve includes a valve casing, which has a valve hole, a spool valve, which is accommodated in the valve hole in a reciprocally movable manner, a supply port, a first output port, a second output port, and a discharge port. The supply port, the first output port, the second output port, and the discharge port communicate with the valve hole. The spool valve reciprocates in the valve hole to switch between a first switching position and a second switching position. When the spool valve is located at the first switching position, the supply port and the first output port communicate with each other and the second output port and the discharge port communicate with each other. When the spool valve is located at the second switching position, the supply port and the second output port communicate with each other and the first output port and the discharge port communicate with each other.
For the electromagnetic valve, as disclosed in Japanese Patent No. 4072756, for example, there is a method that uses pressure sensors to detect the operating state of the spool valve. In the electromagnetic valve of the aforementioned publication, a first pressure sensor and a second pressure sensor are mounted on a single substrate. The first pressure sensor is fitted in a first pressure introduction hole, which communicates with the first output port. A first sealing member is arranged between the first pressure sensor and the first pressure introduction hole. The first sealing member thus prevents leakage of fluid from between the first pressure sensor and the first pressure introduction hole. The first pressure sensor detects the pressure of the fluid output from the first output port. Similarly, the second pressure sensor is fitted in a second pressure introduction hole, which communicates with the second output port. A second sealing member is arranged between the second pressure sensor and the second pressure introduction hole. The second sealing member thus prevents leakage of fluid from between the second pressure sensor and the second pressure introduction hole. The second pressure sensor detects the pressure of the fluid output from the second output port.
In the electromagnetic valve of the aforementioned publication, the single substrate, on which the first and second pressure sensors are mounted, is arranged such that the first pressure sensor and the second pressure sensor are fitted in the first pressure introduction hole and the second pressure introduction hole, respectively. Therefore, errors exist in the distance between the first pressure sensor and the second pressure sensor and in the distance between the first pressure introduction hole and the second pressure introduction hole, the axis of each of the first and second pressure sensors may be offset from the axis of the associated one of the first and second pressure introduction holes. This lowers the sealing performance of the first and second sealing members. Also, when the first pressure sensor and the second pressure sensor are mounted on a single substrate, the substrate has an enlarged planar size. This enlarges the size of the electromagnetic valve in the planar direction of the substrate. Additionally, improvement in the ease of maintenance of the electromagnetic valve is desired.